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Anti-apoptotic role of caspase-cleaved GAB1 adaptor protein in hepatocyte growth factor/scatter factor-MET receptor protein signaling.

ABSTRACT: The GRB2-associated binder 1 (GAB1) docking/scaffold protein is a key mediator of the MET-tyrosine kinase receptor activated by hepatocyte growth factor/scatter factor (HGF/SF). Activated MET promotes recruitment and tyrosine phosphorylation of GAB1, which in turn recruits multiple proteins and mediates MET signaling leading to cell survival, motility, and morphogenesis. We previously reported that, without its ligand, MET is a functional caspase target during apoptosis, allowing the generation of a p40-MET fragment that amplifies apoptosis. In this study we established that GAB1 is also a functional caspase target by evidencing a caspase-cleaved p35-GAB1 fragment that contains the MET binding domain. GAB1 is cleaved by caspases before MET, and the resulting p35-GAB1 fragment is phosphorylated by MET upon HGF/SF binding and can interact with a subset of GAB1 partners, PI3K, and GRB2 but not with SHP2. This p35-GAB1 fragment favors cell survival by maintaining HGF/SF-induced MET activation of AKT and by hindering p40-MET pro-apoptotic function. These data demonstrate an anti-apoptotic role of caspase-cleaved GAB1 in HGF/SF-MET signaling.

SUBMITTER: Le Goff A

PROVIDER: S-EPMC3471683 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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Anti-apoptotic role of caspase-cleaved GAB1 adaptor protein in hepatocyte growth factor/scatter factor-MET receptor protein signaling.

Le Goff Arnaud A Ji Zongling Z Leclercq Bérénice B Bourette Roland P RP Mougel Alexandra A Guerardel Cateline C de Launoit Yvan Y Vicogne Jérôme J Goormachtigh Gautier G Fafeur Véronique V

The Journal of biological chemistry 20120822 42

The GRB2-associated binder 1 (GAB1) docking/scaffold protein is a key mediator of the MET-tyrosine kinase receptor activated by hepatocyte growth factor/scatter factor (HGF/SF). Activated MET promotes recruitment and tyrosine phosphorylation of GAB1, which in turn recruits multiple proteins and mediates MET signaling leading to cell survival, motility, and morphogenesis. We previously reported that, without its ligand, MET is a functional caspase target during apoptosis, allowing the generation ...[more]

PMID: 22915589

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Project description:MET, the receptor for hepatocyte growth factor (HGF), is involved in wide variety of biological events and its aberrant activation is implicated in the pathogenesis of cancer. Especially, MET signaling is associated with resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), key drugs in therapy of non-small cell lung cancer. MET has 11 potential N-glycosylation sites, however, the site-specific roles of N-glycans have not been elucidated. Here, we report that N-glycans regulate proteolytic processing of MET and HGF induced MET signaling, site specifically. N-glycosylation inhibitors suppressed processing and trafficking of endogenous MET in H1975 and EBC-1 lung cancer cells and exogenous MET in CHO cells. We purified the recombinant extracellular domain of human MET and determined the site-specific N-glycan structures and occupancy using nanoflow liquid chromatography-electrospray ionization mass spectrometry. The results indicated that most sites were fully glycosylated and the dominant population were complex-type which were rich in sialic acids and core fucoses. To examine the effects of N-glycan deletion of MET, we prepared endogenous-MET-knockout Flp-In CHO cells and transfected with series of N-glycan deletion mutants of MET. It was found that several N-glycans are implicated in processing of MET. It was also suggested that the N-glycans of -subunit of MET positively regulate HGF signaling, and the N-glycans of β-subunit negatively regulate HGF signaling. In all-N-glycan deletion mutant, processing and signaling were significantly suppressed. It was observed that the cell proliferation rate was suppressed in all-N-glycan deletion mutant, although the cell surface expression levels of MET were not completely diminished. We examined the HGF biding affinity for the recombinant extracellular domain of MET and found that peptide N-glycosidase F treatment did not affect the ligand binding affinity. It was suggested that N-glycans of MET affect the status and the function of the receptor site-specifically.

Dataset Information

Anti-apoptotic role of caspase-cleaved GAB1 adaptor protein in hepatocyte growth factor/scatter factor-MET receptor protein signaling.

Publications

Anti-apoptotic role of caspase-cleaved GAB1 adaptor protein in hepatocyte growth factor/scatter factor-MET receptor protein signaling.

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